Process for the preparation of proteinureic fibres and mixed protein-ureic cellulosic fibres



April 20, 1965 s. DONINI 3,1 PROCESS FOR THE PREPARA N OF PRO N" ICFIBRES AND RES MIXED PROTEIN- IC CELLU IC B Filed Feb. 7, 1962 UnitedStates Patent PRUCESS FOR THE PREPARATION OF PROTEIN- UREIC FIBRES ANDMIXED PROTEHN-UREEC CELLULOSEC FIBRES Sandro Domini, Vials F. Crispi 13,Milan, Ital3 Filed Feb. 7, 1962, Ser. No. 171,604 Claims priority,application Italy, Feb. 7, 1961, 646,461 3 Claims. (Cl. 264-202) Thepresent invention refers to a process for making protein-ureicartificial fibres and mixed protein-ureiccellulosic fibers.

In the technics of the manufacture of artificial textile fibres, thoseobtained by spinning colloidal solutions of protein or, more exactly, ofalkaline substitution products of the same, in an acid coagulation bath,are well known; a typical example of such fibres is the very well knownartificial fibre, similar to wool, obtained by spinning a colloidalsolution of sodium caseinate in an acid coagulating bath.

Mixed fibres of sodium caseinate and viscose are also well known.

These artificial fibres, and the process of preparing them, were fullydescribed for example in Italian Patents Nos. 348,661 and 367,405.

From an examination of these previous technical documents it can be seenat once that at that time it was considered imperative not to use caseinwith its original degree of acidity (pH 5.5-6.5) but to operatedefinitely in an alkaline environment: moreover, as was pointed out inItalian Patent 348,661, only sodium and potassium salts were consideredsuitable at that time for the formation of solutions of casein capableof being spun.

The surprising discovery has now been made, and this constitutes theessential characteristics of the present invention, that it is not onlypossible to obtain spinnable solutions of casein although maintainingthe original acidity of the casein, but that proteic fibres can beobtained with characteristics of spinnability, appearance, handle,heat-insulation and even microscopic structure much nearer to those ofnatural wool than those of the artificial wools which were obtained byspinning alkaline caseinates: it may be pointed out here that theproducts of this invention must not be considered as modifications ofthe caseinic fibres known hitherto, but rather as products verydifferent from those known up to now. Products obtained with thisinvention have excellent dyeing properties with all textile dyestuffs,especially with the acid dyes called half wool.

Broadly speaking, this invention foresees the preparation of spinnablecasein solutions obtained by emulsifying, in an aqueous stage, lacticcasein and urea. In this way a colloidal solution is obtained, free fromany combined or added alkali, and which can easily be spun; this colloidhas in fact such a high spinnability that it can be spun even by simplydropping into water.

It must be added, however, that the preparation of the aqueous solutionof casein and urea must be carried out whilst observing some essentialconditions, failing which it is not possible to obtain the desiredperfect results.

in general, it is essential that the preparation of the emulsion in anaqueous phase, of casein and urea should not take place by introducingthe aqueous dispersive phase all at once into the casein-urea mixture.

The process according to this invention is characterized by comprisingthe operations of mixing lactic casein and urea mechanically, preferablyin the presence of a tensionactive agent, for example ethyl alcohol, forat least 30 minutes until a homogeneous mixture is obtained, adding upto 30% by volume of water necessary to form a colloidal solution of therequired concentration and mixing arrears Patented Apr. 20, 1965 slowlyfor at least minutes; adding the remaining quantity of water slowlyduring the subsequent 90 minutes, stirring for a further 3 hours,preferably leaving the solution thus obtained to mature for at least 16hours at a temperature between 20 C. and 24 C.

Once these operations have been carried out spinning can be undertakenwithout delay, using the standard spinnerets for rayon and otherartificial fibres and any one of the known acid coagulating baths: asalready mentioned it is quite possible to carry out the spinning inwater in view of the insolubility of the colloid, but for obvioustechnical reasons it is preferable to use an acid coagulating bath, forinstance a bath of sulphuric acid, sodium chloride, sulphate of zinc (orsulphate of aluminum).

The usual coagulating baths for rayon can safely be used.

The accompanying drawings show: in FIG. 1 a crosssection of filaments ofcasein-urea (70%), in FIG. 2 a cross-section of filaments of casein-ureaand cellulose (30%).

It must also be pointed out, and this will be illustrated with severalexamples, that the casein-urea combination according to the presentinvention is very suitable for mixing with viscose, and this makes itpossible to obtain valuable composite fibres.

The examples which follow illustrate, without restrictive eifect, thevarious aspects of the invention.

Example 1 4-0 kg. of urea are placed into a mixer and 1.5 litres ofethyl alcohol are added, mixing for 1015 minutes until a homogeneousmixture is obtained. Now add 60 kg. of casein and mix again for at least30 minutes. The emulsion can now be prepared, and great attention mustbe paid to the method of procedure, which is of very great importancefor the purpose of this invention. In general, emulsions should beprepared with a concentration above 30% of casein-urea in water, as withweaker concentrations the solid products may precipitate.

In the present case we shall consider an emulsion of about 30%, whichhas given excellent results in practical use.

In order to prepare such a solution about 50 kg. of the casein-ureaalcohol mixture, prepared as above, will be taken, and litres of water.Obviously the water must not be excessively hard: for preference thehardness should not be above 30 French degrees, but this is not a hardand fast limit.

First of all the 50 kilos of casein-urea-alcohol mixture and 30 litresof water should be put into the mixer and mixed slowly for at least anhour and a half.

Afterwards the remaining 70 litres of water should be poured, from acalibrated receptacle and in a thin stream, for another 90 minutes atleast, stirring slowly; the mixer should make from 12 to 18 revolutionsper minute.

Great attention should be paid whilst pouring the last 15 litres ofwater to ensure that the casein-urea mixture swells up properly andforms a homogeneous colloidal solution. The mixer should therefore beleft running for another 3 hours and thus the colloidal solution, aftermaturing for about 24 hours at a temperature between 22 C. and 24 C.,will be ready for spinning in any form desired.

Example 2 1200 kg. of viscose must be mixed with 9% cellulose and kg. ofcasein-urea emulsion about 30%, the latter prepared by the sameprocedure as in Example 1. The mixture of this emulsion and of theviscose is homogenized in a mixture, and after the phase of de-aerationand maturing one obtains for spinning in an acid coagulata ing bath (forinstance: 7% H 80 16% NaCl; 10% ZuSO or Al(SO density 1.2751.3) a yarnwhich is completely different in appearance from the artificial silkyarn obtained by the viscose or cupraammonium process and with excellentcharacteristics as regards strength and behaviour in weaving.

The processes of desulphurization and washing, necessary owing to thepresence of the viscose, may be carried out in accordance with the usualpractice; for bleaching it is advisable to use hydrogen peroxideacidified up to pH 66.5 with acetic acid.

The finishing bath with softener can be a normal neutral bath.

Example 3 800 kg. of about 10% viscose solution are mixed with 250 kg.of 33% casein-urea emulsion prepared according to the proceduredescribed in Example 1. The mixture obtained in this Way, as it is easyto calculate, contains about equal quantities by weight of casein-ureaand viscose; it should be borne in mind that the parts and percentagesare indicated by weight.

This mixture, after being homogenized, de-aerated and a more accentuatedelastic retardation than the yarn in iating bath. Yarns obtained in thisway show greater and a more accentuated elastic retardation the yarn inExample 2.

I claim:

1. A process for the preparation of artificial fibres using acidiclactic casein and urea as the starting materiais, comprising the stepsof:

(a) mechanically and intimately admixing acidic lactic casein and ureafor at least 30 minutes until a homogeneous mixture of said ingredientsis achieved;

([2) adding to said mixture a minor fraction of the volume of waterwhich is necessary to form a colloidal solution in water of saidingredients and slow- 1y stirring the resultant mixture for at least 90minutes;

(c) adding to the slurry thus obtained the remaining fraction of saidwater volume necessary to form said colloidal solution and stirring forat least 3 additional hours;

(d) allowing the resultant aqueous mixture to ripen for at least 24hours at a temperature in the range 20 C.-24 (3., and

(e) spinning the thus obtained spinnable casein-urea compound in anacidic coagulation bath to obtain said artificial casein-urea fibres.

2. A process according to claim 1, wherein said mixture of casein andurea as specified in step (a) of claim 1 is prepared in ethanol.

3. A process according to claim 1, wherein a cellulose xanthate solutionin carbon disulphide is added to said ripened spinnable casein-ureacompound and intimately admixed therewith before spinning.

References Cited by the Examiner UNITED STAT ES PATENTS 2,291,701. 8/42Dreyfus 18-54 2,318,544 5/43 Thurmond et al. 264202 2,342,994 2/44Atwood 18-54 2,358,383 9/44 Chibnall et al 1854 2,398,625 4/46 Kadt 18542,516,700 7/50 Holloway et al 106-146 2,548,357 4/51 Perrctti 2642=()2FOREIGN PATENTS 483,731 4/38 Great Britain.

ALEXANDER H. BRODMERKEL, Primary Examiner.

MORRIS LIEBMAN, Examiner.

1. A PROCESS FOR THE PREPARATION OF ARTIFICIAL FIBRES USING ACIDICLACTIC CASEIN AND UREA AS THE STARTNG MATERIALS, COMPRISING THE STEPSOF: (A) MECHANICALLY AND INITIMATELY ADMIXING ACIDIC LACTIC CASEIN ANDUREA FOR AT LEAST 30 MINUTES UNTIL A HOMOGENEOUS MIXTURE OF SAIDINGREDIENTS IS ACHIEVED; (B) ADDING TO SAID MIXTURE A MINOR FRACTION OFTHE VOLUME OF WATER WHICH IS NECCESSARY TO FORM A COLLOIDAL SOLUTION INWATER OF SAID INGREDIENTS AND SLOWLY STIRRING THE RESULTANT MIXTURE FORAT LEAST 90 MINUTES; (C) ADDING TO THE SLURRY THUS OBTAINED THEREMAINING FRACTION OF SAID WATER VOLUME NECCESSARY TO FORM SAIDCOLLOIDAL SOLUTION AND STIRRING FOR AT LEAST 3 ADDITIONAL HOURS; (D)ALLOWING THE RESULTANT AQUEOUS MIXTURE TO RIPEN FOR AT LEAST 24 HOURS ATA TEMPERATURE IN THE RANGE 20*C-24*C., AND (E) SPINNING THE THUSOBTAINED SPINNABLE CASEIN-UREA COMPOUND IN AN ACDIC COAGULATION BATH TOOBTAIN SAID ARTIFICIAL CASEIN-UREA FIBERS.